1. FIELD OF THE INVENTION
The present invention relates to compositions which generate little odorous components and are excellent thermal stability, to multilayered containers which can pack and contain various foods, in particular various liquid foods and beverages, e.g. straight juices of citrus fruits, such as orange juice and lemon juice, as well as cosmetics, perfumes, etc., without impairing their good flavor and/or good odor, and further to packages, particularly food packages, comprising such containers containing various contents, with high quality and excellent keeping property.
2. DESCRIPTION OF THE PRIOR ART
Recently, as containers for liquid foods and the like, besides conventional glass bottles and metal cans, multilayered structures comprising thermoplastic resins and composite containers comprising paper and thermoplastic resin layers have been widely used.
In keeping with this movement, there has been a problem of deterioration of the contents, especially of foods. Particularly, when the contents are juices of citrus fruits or foods containing such fruits, terpene hydrocarbons such as d-limonene which constitute the flavor component tend to be absorbed in polyolefins such as polyethylene, which are widely used for the innermost layer of such containers. The reduction of the flavor components of a food during its storage necessarily leads to deterioration of the flavor, thereby minimizing its commercial value.
In the case where a saponified product of an ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) is used instead of polyolefin resins for the innermost layer, the absorption of the flavor components is, as described in Japanese Patent Application Laid-open No. 3950/1988, markedly reduced and the flavor does hence not deteriorate so much. However, conventional EVOH has still the following problem. Containers comprising conventional EVOH often produce an irritating odor due to isolation of residual acetic acid, or produce acetaldehyde, crotonaldehyde, aldol or the like as its pyrolysate, so that the containers cannot exhibit a sufficient preservability for food flavors. Even when the contents are good-smelling cosmetics or perfumes, which are non-foods, their odors deteriorate from the same reason, which is not preferred.
Japanese Patent Application Laid-open Nos. 955/1977, 49294/1976 and 143954/1987 disclose the incorporation into EVOH of metal salts and acetic acid for the purpose of providing the EVOH with thermal stability. The former two have not been able to succeed in suppressing generation of odorous components because of large incorporation of acetic acid, and the latter does not have sufficient thermal stability because of the use of the specific metal phosphates and further is not given consideration for suppressing generation of odorous components at all. Furthermore, none the above literature describes about the provision of the EVOH composition at the innermost layer of a multilayered container.